Ayman, Neil -
Here is where it should appear on the ribbon. (The directions Ayman quoted mention looking underthe tab, which is misleading; just want to double-check that you're looking in the right spot.)
If that's not the issue, do you mind sharing your exact version number? In Excel, go to File > Account. The version is listed under the Office Updates section. As Hans mentions, this feature is (or will be) available in subscription versions of Office 2016, but not in Office 2016 versions obtained as a one-time purchase.
Thanks!